Spatiotemporal drivers of energy expenditure in a coastal marine fish

Animal behavior and energy expenditure often vary significantly across the landscape, and quantifying energy expenditure over space and time provides mechanistic insight into ecological dynamics. Yet, spatiotemporal variability in energy expenditure has rarely been explored in fully aquatic species such as fish. Our objective was to quantify spatially explicit energy expenditure for a tropical marine teleost fish, bonefish (Albula vulpes), to examine how bonefish energetics vary across landscape features and temporal factors. Using a swim tunnel respirometer, we calibrated acoustic accelerometer transmitters implanted in bonefish to estimate their metabolic rates and energy expenditure, and applied this technology in situ using a fine-scale telemetry system on a heterogeneous reef flat in Puerto Rico. Bonefish energy expenditure varied most among habitats, with significant interactions between habitat and temporal factors (i.e., diel period, tide state, season). The energy expenditure was generally highest in shallow water habitats (i.e., seagrass and reef crest). Variation in activity levels was the main driver of these differences in energy expenditure, which in shallow, nearshore habitats is likely related to foraging. Bonefish moderate energy expenditure across seasonal fluctuations in temperature, by selectively using shallow nearshore habitats at moderate water temperatures that correspond with their scope for activity. Quantifying how animals expend energy in association with environmental and ecological factors can provide important insight into behavioral ecology, with implications for bioenergetics models

Post-release behaviour and survival of recreationally-angled arapaima (Arapaima cf. arapaima) assessed with accelerometer biologgers

Recreational fisheries are increasingly important sectors of tourism-based economies. In the last decade, new recreational fisheries have emerged that target species of varying conservation status including vulnerable, endangered, and unassessed species. In Guyana, catch-and-release angling tourism has begun to target arapaima, a genus of giant air-breathing fishes. Given the uncertain conservation status of this species and that no information is available to evaluate the sustainability of this activity, we sought to describe the responses of arapaima to recreational angling. We harnessed tri-axial accelerometer biologgers around the trunk of fish that had been captured and released by recreational anglers, allowing us to monitor post-release survival and behaviour, including surfacing, which is essential for this air-breathing fish to recover from exhaustion. Twenty-seven individuals were instrumented (162 ± 25 cm), 24 of which were considered survivors (89%) during the 47 ± 35 (SD) min monitoring period. Fish that died were observed to drown soon after release (i.e. within minutes), not surfacing to breathe air. Supervised machine learning classification of behaviours using a random forest algorithm identified surfacing events with 80% accuracy (i.e. out-of-bag error rate = 20%), which we applied to unobserved data periods to estimate breathing frequency after release, along with overall dynamic body acceleration (ODBA) as a proxy for activity. Neither mean breathing frequency nor ODBA were related to body size (total length), handling time (which incorporated facilitated recovery of individual

Estimating fish swimming metrics and metabolic rates with accelerometers: the influence of sampling frequency

Accelerometry is growing in popularity for remotely measuring fish swimming metrics, but appropriate sampling frequencies for accurately measuring these metrics are not well studied. This research examined the influence of sampling frequency (1–25 Hz) with tri-axial accelerometer biologgers on estimates of overall dynamic body acceleration (ODBA), tail-beat frequency, swimming speed and metabolic rate of bonefish Albula vulpes in a swim-tunnel respirometer and free-swimming in a wetland mesocosm. In the swim tunnel, sampling frequencies of ≥ 5 Hz were sufficient to establish strong relationships between ODBA, swimming speed and metabolic rate. However, in free-swimming bonefish, estimates of metabolic rate were more variable below 10 Hz. Sampling frequencies should be at least twice the maximum tail-beat frequency to estimate this metric effectively, which is generally higher than those required to estimate ODBA, swimming speed and metabolic rate. While optimal sampling frequency probably varies among species due to tail-beat frequency and swimming style, this study provides a reference point with a medium body-sized sub-carangiform teleost fish, enabling researchers to measure these metrics effectively and maximize study duration

Collaboration and engagement produce more actionable science: quantitatively analyzing uptake of fish tracking studies

Aquatic telemetry technology generates new knowledge about the underwater world that can inform decision-making processes and thus can improve conservation and natural resource management. Still, there is lack of evidence on how telemetry-derived knowledge can or has informed management, and what factors facilitate or deter its use. We present one of the first quantitative studies related to the science-action gap and evaluate factors that influence the uptake of fish telemetry findings into policies and practices, as well as social acceptance of these findings. We globally surveyed 212 fish telemetry researchers regarding the knowledge uptake of an applied fish telemetry research project of their choice. Respondents’ personal and professional attributes, as well as the attributes of their chosen projects, were analyzed using machine learning algorithms to identify important factors that influenced the uptake (i.e., use, trust, and/or acceptance) of their findings. Researchers with extensive collaborations and who spent more time engaging in public outreach experienced greater uptake of their findings. Respondents with greater telemetry experience and commitment (e.g., more telemetry publications, higher proportion of research on fish telemetry) tended to achieve more social acceptance of their findings. Projects led by researchers who were highly involved and familiar with the fisheries management processes, and those where greater effort was devoted to research dissemination, also tended to experience greater uptake. Last, the levels of complexity and controversy of the issue addressed by the research project had a positive influence on the uptake of findings. The empirical results of this study support recent messages in the science practitioner literature for greater collaboration, knowledge co-production with partners, and public engage

An experimental evaluation of the role of the stress axis in mediating predator-prey interactions in wild marine fish

The hypothalamic-pituitary-interrenal (HPI) axis, through corticosteroid secretion, is an integral mechanism regulating internal homeostasis when vertebrates are faced with a stressor. However, continued HPI-axis stimulation can produce homeostatic overload, where corticosteroids are detrimental to organismal function. This overload condition may play an important role in mediating predator-prey interactions, because chronically/previously stressed animals may have higher rates of predator-induced mortality. However, the mechanism(s) underlying this observation are unknown. Using fish as models, we hypothesized that chronic stress would increase predation susceptibility owing to a poor physiological state (e.g. homeostatic overload) with corresponding sub-optimal changes in predator-avoidance behaviour. As cortisol is also required in low quantities to help regulate basic metabolic functions in fish, we expected that a glucocorticoid receptor antagonist (GR; e.g. homeostatic failure) may produce similar effects. Schoolmaster snapper (Lutjanus apodus) were given intraperitoneal implants of cocoa butter impregnated with nothing (sham; 5 ml/kg body weight (BW)), cortisol (50 mg/kg BW) or the GR antagonist RU486 (100 mg/kg BW). At 24-h post-implantation, fish were tethered to the seafloor and observed for behavioural metrics associated with predation. Blood samples were collected from a subset of fish to assess the physiological consequences of the implants. Cortisol- and RU486-implanted fish both had significantly higher plasma cortisol concentrations than sham fish, with blood glucose and plasma urea being elevated only in the former. Furth

Consequences of Different Types of Littoral Zone Light Pollution on the Parental Care Behaviour of a Freshwater Teleost Fish

Ecological light pollution occurs when artificial lights disrupt the natural regimes of individual organisms or their ecosystems. Increasing development of shoreline habitats leads to increased light pollution (e.g., from cottages, docks, automobile traffic), which could impact the ecology of littoral zones of lakes and rivers. Smallmouth bass (Micropterus dolomieu) engage in sole paternal care, guarding their nest continually, day and night, to protect their developing offspring. Any alterations to their behaviour—either directly because of the response to light or indirectly due to changes in nest predator activity and associated response of the bass—could lead to increased energetic demands for fish that have a fixed energy budget and ultimately reduce reproductive success. To examine this issue, tri-axial accelerometer biologgers were externally attached to nesting smallmouth bass during the egg stage to determine whether light pollution (i.e., dock lights with low levels of continuous lig

Swimming speeds and metabolic rates of semi-captive juvenile lemon sharks (Negaprion brevirostris, Poey) estimated with acceleration biologgers

There is much interest in being able to quantify the swimming speeds and metabolic rates of wild aquatic animals such as sharks to develop bioenergetics models and evaluate the metabolic consequences of different stressors. This study sought to calibrate tri-axial acceleration biologgers (accelerometers) such that it would be possible to estimate swimming speeds and metabolic rates of semi-captive sharks in an enclosed natural mesocosm. Juvenile lemon sharks (Negaprion brevirostris, Poey; 60–75 cm total length, 1–2 kg) were equipped with accelerometers and swum at stepwise velocity increments in a Blazka-style swim tunnel respirometer using a critical swimming speed protocol. Metabolic rates and acceleration-derived metrics (overall dynamic body acceleration and tailbeat frequency) were measured concurrently during forced swimming, and accelerometer-equipped sharks were released to an enclosed mesocosm habitat to estimate average daily metabolic rate (ADMR) and swimming velocities across diel and tidal cycles. Acceleration-derived tailbeat frequency was a stronger predictor of metabolic rate than overall dynamic body action, and predicted an active metabolic rate of 249.7 ± 1.9 mg O2 kg− 1 h− 1 and an ADMR of 88.7 ± 0.7 kJ kg− 1 d− 1 at 30 °C. Following exhaustive exercise a maximum metabolic rate of 398.0 ± 19.6 mg O2 kg− 1 h− 1 was achieved and over the s

As I see it: On the neglected cold side of climate change and what it means to fish

Over the past decade nearly all of the research on the effects of climate change on fish has focused on the effects of warmer water temperatures. Yet, it is expected that temperature variability will also increase, resulting in more frequent incidences of rapid decreases in water temperatures (i.e. cold shock). Cold shock events have caused large-scale fish mortalities, and sublethal impacts are also known to occur but are less well documented. We argue that cold shock will become an important selective force in climate change scenarios. There is a rich history of research on cold shock in the context of industrial cooling effluents and aquaculture, providing a foundation upon which to develop and extend future work on cold shock and climate change. To understand the diverse effects climate change may have on fish populations, future research needs to expand beyond the projected increases in water temperatures to include consideration of variability in temperature and the potential for cold shock

Influence of supraphysiological cortisol manipulation on predator avoidance behaviors and physiological responses to a predation threat in a wild marine teleost fish

The stress axis in teleost fish attempts to maintain internal homeostasis in the face of allostatic loading. However, stress axis induction has been associated with a higher predation rate in fish. To date, the physiological and behavioral factors associated with this outcome are poorly understood. The purpose of the present study was to investigate the impact of experimental cortisol elevation on anti-predator behavior and physiological responses to predator presence. We hypothesized that semi-chronic cor

Fine-scale movement and activity patterns of Caribbean reef sharks (Carcharhinus perezi) in the Bahamas

Knowledge of the spatial ecology and movement of animals contributes to our understanding of intra- and inter-specific interactions and ecosystem dynamics, and can inform conservation actions. Here we assessed the space use and activity levels of a marine predator, the Caribbean reef shark (Carcharhinus perezi), in coastal regions of Eleuthera, The Bahamas over a 60-day period using acoustic telemetry. Of the 14 adult sharks (eight males, six females) tagged with acoustic transmitters (equipped with accelerometer sensor), nine were detected in a 14 km2 gridded receiver array. Male sharks were significantly less likely to be detected over time relative to females. Given post-release survival is typically high in C. perezi, this finding may indicate that males have larger home ranges and may exhibit lower site fidelity compared to females. Patterns of space use indicated C. perezi primarily oc